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{{task|Sorting Algorithms}}{{Sorting Algorithm}}
;Task: Sort an [[array]] (or list) of elements using the Selection sort algorithm.
It works as follows:
First find the smallest element in the array and exchange it with the element in the first position, then find the second smallest element and exchange it with the element in the second position, and continue in this way until the entire array is sorted.
Its asymptotic complexity is [O] making it inefficient on large arrays.
Its primary purpose is for when writing data is very expensive (slow) when compared to reading, eg. writing to flash memory or EEPROM.
No other sorting algorithm has less data movement.
;Reference:
- Wikipedia: [[wp:Selection_sort|Selection sort]]
360 Assembly
{{trans|PL/I}} The program uses ASM structured macros and two ASSIST macros to keep the code as short as possible.
* Selection sort 26/06/2016
SELECSRT CSECT
USING SELECSRT,R13 base register
B 72(R15) skip savearea
DC 17F'0' savearea
STM R14,R12,12(R13) prolog
ST R13,4(R15) "
ST R15,8(R13) "
LR R13,R15 "
LA RJ,1 j=1
DO WHILE=(C,RJ,LE,N) do j=1 to n
LR RK,RJ k=j
LR R1,RJ j
SLA R1,2 .
LA R3,A-4(R1) @a(j)
L RT,0(R3) temp=a(j)
LA RI,1(RJ) i=j+1
DO WHILE=(C,RI,LE,N) do i=j+1 to n
LR R1,RI i
SLA R1,2 .
L R2,A-4(R1) a(i)
IF CR,RT,GT,R2 THEN if temp>a(i) then
LR RT,R2 temp=a(i)
LR RK,RI k=i
ENDIF , end if
LA RI,1(RI) i=i+1
ENDDO , end do
L R0,0(R3) a(j)
LR R1,RK k
SLA R1,2 .
ST R0,A-4(R1) a(k)=a(j)
ST RT,0(R3) a(j)=temp;
LA RJ,1(RJ) j=j+1
ENDDO , end do
LA R3,PG pgi=0
LA RI,1 i=1
DO WHILE=(C,RI,LE,N) do i=1 to n
LR R1,RI i
SLA R1,2 .
L R2,A-4(R1) a(i)
XDECO R2,XDEC edit a(i)
MVC 0(4,R3),XDEC+8 output a(i)
LA R3,4(R3) pgi=pgi+4
LA RI,1(RI) i=i+1
ENDDO , end do
XPRNT PG,L'PG print buffer
L R13,4(0,R13) epilog
LM R14,R12,12(R13) "
XR R15,R15 "
BR R14 exit
A DC F'4',F'65',F'2',F'-31',F'0',F'99',F'2',F'83',F'782',F'1'
DC F'45',F'82',F'69',F'82',F'104',F'58',F'88',F'112',F'89',F'74'
N DC A((N-A)/L'A) number of items of a
PG DC CL80' ' buffer
XDEC DS CL12 temp for xdeco
YREGS
RI EQU 6 i
RJ EQU 7 j
RK EQU 8 k
RT EQU 9 temp
END SELECSRT
{{out}}
-31 0 1 2 2 4 45 58 65 69 74 82 82 83 88 89 99 104 112 782
ActionScript
function selectionSort(input: Array):Array {
//find the i'th element
for (var i:uint = 0; i < input.length; i++) {
//set minIndex to an arbitrary value
var minIndex:uint=i;
//find the smallest number
for (var j:uint = i; j < input.length; j++) {
if (input[j]<input[minIndex]) {
minIndex=j;
}
}
//swap the smallest number into place
var tmp:Number=input[i];
input[i]=input[minIndex];
input[minIndex]=tmp;
}
return input;
}
Ada
with Ada.Text_IO; use Ada.Text_IO;
procedure Test_Selection_Sort is
type Integer_Array is array (Positive range <>) of Integer;
procedure Sort (A : in out Integer_Array) is
Min : Positive;
Temp : Integer;
begin
for I in A'First..A'Last - 1 loop
Min := I;
for J in I + 1..A'Last loop
if A (Min) > A (J) then
Min := J;
end if;
end loop;
if Min /= I then
Temp := A (I);
A (I) := A (Min);
A (Min) := Temp;
end if;
end loop;
end Sort;
A : Integer_Array := (4, 9, 3, -2, 0, 7, -5, 1, 6, 8);
begin
Sort (A);
for I in A'Range loop
Put (Integer'Image (A (I)) & " ");
end loop;
end Test_Selection_Sort;
{{out}}
-5 -2 0 1 3 4 6 7 8 9
ALGOL 68
{{trans|Ada}}
{{works with|ALGOL 68|Standard - no extensions to language used}} {{works with|ALGOL 68G|Any - tested with release mk15-0.8b.fc9.i386}} {{works with|ELLA ALGOL 68|Any (with appropriate job cards) - tested with release 1.8.8d.fc9.i386}}
MODE DATA = REF CHAR;
PROC in place selection sort = (REF[]DATA a)VOID:
BEGIN
INT min;
DATA temp;
FOR i FROM LWB a TO UPB a DO
min := i;
FOR j FROM i + 1 TO UPB a DO
IF a [min] > a [j] THEN
min := j
FI
OD;
IF min /= i THEN
temp := a [i];
a [i] := a [min];
a [min] := temp
FI
OD
END # in place selection sort #;
[32]CHAR data := "big fjords vex quick waltz nymph";
[UPB data]DATA ref data; FOR i TO UPB data DO ref data[i] := data[i] OD;
in place selection sort(ref data);
FOR i TO UPB ref data DO print(ref data[i]) OD; print(new line);
print((data))
{{out}}
abcdefghiijklmnopqrstuvwxyz
big fjords vex quick waltz nymph
ARM Assembly
{{works with|as|Raspberry Pi}}
/* ARM assembly Raspberry PI */
/* program selectionSort.s */
/************************************/
/* Constantes */
/************************************/
.equ STDOUT, 1 @ Linux output console
.equ EXIT, 1 @ Linux syscall
.equ WRITE, 4 @ Linux syscall
/*********************************/
/* Initialized data */
/*********************************/
.data
szMessSortOk: .asciz "Table sorted.\n"
szMessSortNok: .asciz "Table not sorted !!!!!.\n"
sMessResult: .ascii "Value : "
sMessValeur: .fill 11, 1, ' ' @ size => 11
szCarriageReturn: .asciz "\n"
.align 4
iGraine: .int 123456
.equ NBELEMENTS, 10
#TableNumber: .int 1,3,6,2,5,9,10,8,4,7
TableNumber: .int 10,9,8,7,6,5,4,3,2,1
/*********************************/
/* UnInitialized data */
/*********************************/
.bss
/*********************************/
/* code section */
/*********************************/
.text
.global main
main: @ entry of program
1:
ldr r0,iAdrTableNumber @ address number table
mov r1,#0
mov r2,#NBELEMENTS @ number of élements
bl selectionSort
ldr r0,iAdrTableNumber @ address number table
bl displayTable
ldr r0,iAdrTableNumber @ address number table
mov r1,#NBELEMENTS @ number of élements
bl isSorted @ control sort
cmp r0,#1 @ sorted ?
beq 2f
ldr r0,iAdrszMessSortNok @ no !! error sort
bl affichageMess
b 100f
2: @ yes
ldr r0,iAdrszMessSortOk
bl affichageMess
100: @ standard end of the program
mov r0, #0 @ return code
mov r7, #EXIT @ request to exit program
svc #0 @ perform the system call
iAdrsMessValeur: .int sMessValeur
iAdrszCarriageReturn: .int szCarriageReturn
iAdrsMessResult: .int sMessResult
iAdrTableNumber: .int TableNumber
iAdrszMessSortOk: .int szMessSortOk
iAdrszMessSortNok: .int szMessSortNok
/******************************************************************/
/* control sorted table */
/******************************************************************/
/* r0 contains the address of table */
/* r1 contains the number of elements > 0 */
/* r0 return 0 if not sorted 1 if sorted */
isSorted:
push {r2-r4,lr} @ save registers
mov r2,#0
ldr r4,[r0,r2,lsl #2]
1:
add r2,#1
cmp r2,r1
movge r0,#1
bge 100f
ldr r3,[r0,r2, lsl #2]
cmp r3,r4
movlt r0,#0
blt 100f
mov r4,r3
b 1b
100:
pop {r2-r4,lr}
bx lr @ return
/******************************************************************/
/* selection sort */
/******************************************************************/
/* r0 contains the address of table */
/* r1 contains the first element */
/* r2 contains the number of element */
selectionSort:
push {r1-r7,lr} @ save registers
mov r3,r1 @ start index i
sub r7,r2,#1 @ compute n - 1
1: @ start loop
mov r4,r3
add r5,r3,#1 @ init index 2
2:
ldr r1,[r0,r4,lsl #2] @ load value A[mini]
ldr r6,[r0,r5,lsl #2] @ load value A[j]
cmp r6,r1 @ compare value
movlt r4,r5 @ j -> mini
add r5,#1 @ increment index j
cmp r5,r2 @ end ?
blt 2b @ no -> loop
cmp r4,r3 @ mini <> j ?
beq 3f @ no
ldr r1,[r0,r4,lsl #2] @ yes swap A[i] A[mini]
ldr r6,[r0,r3,lsl #2]
str r1,[r0,r3,lsl #2]
str r6,[r0,r4,lsl #2]
3:
add r3,#1 @ increment i
cmp r3,r7 @ end ?
blt 1b @ no -> loop
100:
pop {r1-r7,lr}
bx lr @ return
/******************************************************************/
/* Display table elements */
/******************************************************************/
/* r0 contains the address of table */
displayTable:
push {r0-r3,lr} @ save registers
mov r2,r0 @ table address
mov r3,#0
1: @ loop display table
ldr r0,[r2,r3,lsl #2]
ldr r1,iAdrsMessValeur @ display value
bl conversion10 @ call function
ldr r0,iAdrsMessResult
bl affichageMess @ display message
add r3,#1
cmp r3,#NBELEMENTS - 1
ble 1b
ldr r0,iAdrszCarriageReturn
bl affichageMess
100:
pop {r0-r3,lr}
bx lr
/******************************************************************/
/* display text with size calculation */
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
push {r0,r1,r2,r7,lr} @ save registres
mov r2,#0 @ counter length
1: @ loop length calculation
ldrb r1,[r0,r2] @ read octet start position + index
cmp r1,#0 @ if 0 its over
addne r2,r2,#1 @ else add 1 in the length
bne 1b @ and loop
@ so here r2 contains the length of the message
mov r1,r0 @ address message in r1
mov r0,#STDOUT @ code to write to the standard output Linux
mov r7, #WRITE @ code call system "write"
svc #0 @ call systeme
pop {r0,r1,r2,r7,lr} @ restaur des 2 registres */
bx lr @ return
/******************************************************************/
/* Converting a register to a decimal unsigned */
/******************************************************************/
/* r0 contains value and r1 address area */
/* r0 return size of result (no zero final in area) */
/* area size => 11 bytes */
.equ LGZONECAL, 10
conversion10:
push {r1-r4,lr} @ save registers
mov r3,r1
mov r2,#LGZONECAL
1: @ start loop
bl divisionpar10U @ unsigned r0 <- dividende. quotient ->r0 reste -> r1
add r1,#48 @ digit
strb r1,[r3,r2] @ store digit on area
cmp r0,#0 @ stop if quotient = 0
subne r2,#1 @ else previous position
bne 1b @ and loop
@ and move digit from left of area
mov r4,#0
2:
ldrb r1,[r3,r2]
strb r1,[r3,r4]
add r2,#1
add r4,#1
cmp r2,#LGZONECAL
ble 2b
@ and move spaces in end on area
mov r0,r4 @ result length
mov r1,#' ' @ space
3:
strb r1,[r3,r4] @ store space in area
add r4,#1 @ next position
cmp r4,#LGZONECAL
ble 3b @ loop if r4 <= area size
100:
pop {r1-r4,lr} @ restaur registres
bx lr @return
/***************************************************/
/* division par 10 unsigned */
/***************************************************/
/* r0 dividende */
/* r0 quotient */
/* r1 remainder */
divisionpar10U:
push {r2,r3,r4, lr}
mov r4,r0 @ save value
//mov r3,#0xCCCD @ r3 <- magic_number lower raspberry 3
//movt r3,#0xCCCC @ r3 <- magic_number higter raspberry 3
ldr r3,iMagicNumber @ r3 <- magic_number raspberry 1 2
umull r1, r2, r3, r0 @ r1<- Lower32Bits(r1*r0) r2<- Upper32Bits(r1*r0)
mov r0, r2, LSR #3 @ r2 <- r2 >> shift 3
add r2,r0,r0, lsl #2 @ r2 <- r0 * 5
sub r1,r4,r2, lsl #1 @ r1 <- r4 - (r2 * 2) = r4 - (r0 * 10)
pop {r2,r3,r4,lr}
bx lr @ leave function
iMagicNumber: .int 0xCCCCCCCD
AutoHotkey
ahk forum: [http://www.autohotkey.com/forum/topic44657-105.html discussion]
MsgBox % SelecSort("")
MsgBox % SelecSort("xxx")
MsgBox % SelecSort("3,2,1")
MsgBox % SelecSort("dog,000000,xx,cat,pile,abcde,1,cat,zz,xx,z")
SelecSort(var) { ; SORT COMMA SEPARATED LIST
StringSplit a, var, `, ; make array, size = a0
Loop % a0-1 {
i := A_Index, mn := a%i%, j := m := i
Loop % a0-i { ; find minimum
j++
If (a%j% < mn)
mn := a%j%, m := j
}
t := a%i%, a%i% := a%m%, a%m% := t ; swap first with minimum
}
Loop % a0 ; construct string from sorted array
sorted .= "," . a%A_Index%
Return SubStr(sorted,2) ; drop leading comma
}
AWK
function getminindex(gl, gi, gs)
{
min = gl[gi]
gm = gi
for(gj=gi; gj <= gs; gj++) {
if ( gl[gj] < min ) {
min = gl[gj]
gm = gj
}
}
return gm
}
{
line[NR] = $0
}
END { # sort it with selection sort
for(i=1; i <= NR; i++) {
mi = getminindex(line, i, NR)
t = line[i]
line[i] = line[mi];
line[mi] = t
}
#print it
for(i=1; i <= NR; i++) {
print line[i]
}
}
BBC BASIC
DEF PROC_SelectionSort(Size%)
FOR I% = 1 TO Size%-1
lowest% = I%
FOR J% = (I% + 1) TO Size%
IF data%(J%) < data%(lowest%) lowest% = J%
NEXT J%
IF I%<>lowest% SWAP data%(I%),data%(lowest%)
NEXT I%
ENDPROC
C
#include <stdio.h>
void selection_sort (int *a, int n) {
int i, j, m, t;
for (i = 0; i < n; i++) {
for (j = i, m = i; j < n; j++) {
if (a[j] < a[m]) {
m = j;
}
}
t = a[i];
a[i] = a[m];
a[m] = t;
}
}
int main () {
int a[] = {4, 65, 2, -31, 0, 99, 2, 83, 782, 1};
int n = sizeof a / sizeof a[0];
int i;
for (i = 0; i < n; i++)
printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
selection_sort(a, n);
for (i = 0; i < n; i++)
printf("%d%s", a[i], i == n - 1 ? "\n" : " ");
return 0;
}
{{out}}
4 65 2 -31 0 99 2 83 782 1
-31 0 1 2 2 4 65 83 99 782
C++
Uses C++11. Compile with g++ -std=c++11 selection.cpp
#include <algorithm>
#include <iterator>
#include <iostream>
template<typename ForwardIterator> void selection_sort(ForwardIterator begin,
ForwardIterator end) {
for(auto i = begin; i != end; ++i) {
std::iter_swap(i, std::min_element(i, end));
}
}
int main() {
int a[] = {100, 2, 56, 200, -52, 3, 99, 33, 177, -199};
selection_sort(std::begin(a), std::end(a));
copy(std::begin(a), std::end(a), std::ostream_iterator<int>(std::cout, " "));
std::cout << "\n";
}
{{out}}
-199 -52 2 3 33 56 99 100 177 200
C#
This is a generic implementation that works with any type that implements the IComparable interface
where T : IComparable {
public T[] Sort(T[] list) {
int k;
T temp;
for (int i = 0; i < list.Length; i++) {
k = i;
for (int j=i + 1; j < list.Length; j++) {
if (list[j].CompareTo(list[k]) < 0) {
k = j;
}
}
temp = list[i];
list[i] = list[k];
list[k] = temp;
}
return list;
}
}
Example of usage:
String[] str = { "this", "is", "a", "test", "of", "generic", "selection", "sort" };
SelectionSort<String> mySort = new SelectionSort<string>();
String[] result = mySort.Sort(str);
for (int i = 0; i < result.Length; i++) {
Console.WriteLine(result[i]);
}
{{out}}
a
generic
is
of
selection
sort
test
this
Clojure
This is an implementation that mutates a Java arraylist in place.
(import 'java.util.ArrayList)
(defn arr-swap! [#^ArrayList arr i j]
(let [t (.get arr i)]
(doto arr
(.set i (.get arr j))
(.set j t))))
(defn sel-sort!
([arr] (sel-sort! compare arr))
([cmp #^ArrayList arr]
(let [n (.size arr)]
(letfn [(move-min!
[start-i]
(loop [i start-i]
(when (< i n)
(when (< (cmp (.get arr i) (.get arr start-i)) 0)
(arr-swap! arr start-i i))
(recur (inc i)))))]
(doseq [start-i (range (dec n))]
(move-min! start-i))
arr))))
COBOL
PERFORM E-SELECTION VARYING WB-IX-1 FROM 1 BY 1
UNTIL WB-IX-1 = WC-SIZE.
...
E-SELECTION SECTION.
E-000.
SET WC-LOWEST TO WB-IX-1.
ADD 1 WC-LOWEST GIVING WC-START
PERFORM F-PASS VARYING WB-IX-2 FROM WC-START BY 1
UNTIL WB-IX-2 > WC-SIZE.
IF WB-IX-1 NOT = WC-LOWEST
MOVE WB-ENTRY(WC-LOWEST) TO WC-TEMP
MOVE WB-ENTRY(WB-IX-1) TO WB-ENTRY(WC-LOWEST)
MOVE WC-TEMP TO WB-ENTRY(WB-IX-1).
E-999.
EXIT.
F-PASS SECTION.
F-000.
IF WB-ENTRY(WB-IX-2) < WB-ENTRY(WC-LOWEST)
SET WC-LOWEST TO WB-IX-2.
F-999.
EXIT.
Common Lisp
(defun selection-sort-vector (array predicate)
(do ((length (length array))
(i 0 (1+ i)))
((eql i length) array)
(do ((mindex i)
(min (aref array i))
(j i (1+ j)))
((eql j length)
(rotatef (aref array i) (aref array mindex)))
(when (funcall predicate (aref array j) min)
(setf min (aref array j)
mindex j)))))
(defun selection-sort-list (list predicate)
(flet ((min-first (list)
(do ((before-min nil)
(min (first list))
(prev list (rest prev))
(curr (rest list) (rest curr)))
((endp curr)
(if (null before-min) list
(let ((min (cdr before-min)))
(rplacd before-min (cdr min))
(rplacd min list)
min)))
(when (funcall predicate (first curr) min)
(setf before-min prev
min (first curr))))))
(let ((result (min-first list)))
(do ((head result (rest head)))
((endp (rest head)) result)
(rplacd head (min-first (rest head)))))))
(defun selection-sort (sequence predicate)
(etypecase sequence
(list (selection-sort-list sequence predicate))
(vector (selection-sort-vector sequence predicate))))
Example use:
> (selection-sort (list 8 7 4 3 2 0 9 1 5 6) '<)
(0 1 2 3 4 5 6 7 8 9)
> (selection-sort (vector 8 7 4 3 2 0 9 1 5 6) '>)
#(9 8 7 6 5 4 3 2 1 0)
Crystal
This sorts the array in-place.
def selectionSort(array : Array)
(0...array.size-1).each do |i|
nextMinIndex = i
(i+1...array.size).each do |j|
if array[j] < array[nextMinIndex]
nextMinIndex = j
end
end
if i != nextMinIndex
array.swap(i, nextMinIndex)
end
end
end
D
The actual function is very short.
import std.stdio, std.algorithm, std.array, std.traits;
enum AreSortableArrayItems(T) = isMutable!T &&
__traits(compiles, T.init < T.init) &&
!isNarrowString!(T[]);
void selectionSort(T)(T[] data) if (AreSortableArrayItems!T) {
foreach (immutable i, ref d; data)
data.drop(i).minPos[0].swap(d);
} unittest {
int[] a0;
a0.selectionSort;
auto a1 = [1];
a1.selectionSort;
assert(a1 == [1]);
auto a2 = ["a", "b"];
a2.selectionSort;
assert(a2 == ["a", "b"]);
auto a3 = ["b", "a"];
a3.selectionSort;
assert(a3 == ["a", "b"]);
auto a4 = ['a', 'b'];
static assert(!__traits(compiles, a4.selectionSort));
dchar[] a5 = ['b', 'a'];
a5.selectionSort;
assert(a5 == "ab"d);
import std.typecons;
alias Nullable!int N;
auto a6 = [N(2), N(1)];
a6.selectionSort; // Not nothrow.
assert(a6 == [N(1), N(2)]);
auto a7 = [1.0+0i, 2.0+0i]; // To be deprecated.
static assert(!__traits(compiles, a7.selectionSort));
import std.complex;
auto a8 = [complex(1), complex(2)];
static assert(!__traits(compiles, a8.selectionSort));
static struct F {
int x;
int opCmp(F f) { // Not pure.
return x < f.x ? -1 : (x > f.x ? 1 : 0);
}
}
auto a9 = [F(2), F(1)];
a9.selectionSort;
assert(a9 == [F(1), F(2)]);
}
void main() {
auto a = [3, 1, 4, 1, 5, 9, 2, 6, 5, 3, 5, 8, 9, 7, 9, 3, 2];
a.selectionSort;
a.writeln;
}
{{out}}
[1, 1, 2, 2, 3, 3, 3, 4, 5, 5, 5, 6, 7, 8, 9, 9, 9]
Delphi
Array sort
Dynamic array is a 0-based array of variable length
Static array is an arbitrary-based array of fixed length
program TestSelectionSort;
{$APPTYPE CONSOLE}
{.$DEFINE DYNARRAY} // remove '.' to compile with dynamic array
type
TItem = Integer; // declare ordinal type for array item
{$IFDEF DYNARRAY}
TArray = array of TItem; // dynamic array
{$ELSE}
TArray = array[0..15] of TItem; // static array
{$ENDIF}
procedure SelectionSort(var A: TArray);
var
Item: TItem;
I, J, M: Integer;
begin
for I:= Low(A) to High(A) - 1 do begin
M:= I;
for J:= I + 1 to High(A) do
if A[J] < A[M] then M:= J;
Item:= A[M];
A[M]:= A[I];
A[I]:= Item;
end;
end;
var
A: TArray;
I: Integer;
begin
{$IFDEF DYNARRAY}
SetLength(A, 16);
{$ENDIF}
for I:= Low(A) to High(A) do
A[I]:= Random(100);
for I:= Low(A) to High(A) do
Write(A[I]:3);
Writeln;
SelectionSort(A);
for I:= Low(A) to High(A) do
Write(A[I]:3);
Writeln;
Readln;
end.
{{out}}
0 3 86 20 27 67 31 16 37 42 8 47 7 84 5 29
0 3 5 7 8 16 20 27 29 31 37 42 47 67 84 86
String sort
// string is 1-based variable-length array of Char
procedure SelectionSort(var S: string);
var
Lowest: Char;
I, J, M, L: Integer;
begin
L:= Length(S);
for I:= 1 to L - 1 do begin
M:= I;
for J:= I + 1 to L do
if S[J] < S[M] then M:= J;
Lowest:= S[M];
S[M]:= S[I];
S[I]:= Lowest;
end;
end;
// in : S = 'the quick brown fox jumps over the lazy dog'
// out: S = ' abcdeeefghhijklmnoooopqrrsttuuvwxyz'
E
def selectionSort := {
def cswap(c, a, b) {
def t := c[a]
c[a] := c[b]
c[b] := t
println(c)
}
def indexOfMin(array, first, last) {
var min := array[first]
var mini := first
for i in (first+1)..last {
if (array[i] < min) {
min := array[i]
mini := i
}
}
return mini
}
/** Selection sort (in-place). */
def selectionSort(array) {
def last := (array.size()-1)
for i in 0..(last - 1) {
cswap(array, i, indexOfMin(array, i + 1, last))
}
}
}
EasyLang
## EchoLisp
### List sort
```scheme
;; recursive version (adapted from Racket)
(lib 'list) ;; list-delete
(define (sel-sort xs (x0))
(cond
[(null? xs) null]
[else (set! x0 (apply min xs))
(cons x0 (sel-sort (list-delete xs x0)))]))
(sel-sort (shuffle (iota 13)))
→ (0 1 2 3 4 5 6 7 8 9 10 11 12)
;; straightforward and more efficient implementation using list-swap!
(define (sel-sort list)
(maplist (lambda( L)
(first (list-swap! L (first L) (apply min L )))) list))
(sel-sort (shuffle (iota 13)))
→ (0 1 2 3 4 5 6 7 8 9 10 11 12)
Array sort
;; sort an array in place
(define (sel-sort a (amin) (imin))
(define ilast (1- (vector-length a)))
(for [(i ilast)]
(set! amin [a (setv! imin i)]) ;; imin := i , amin := a[imin]
(for [(j (in-range (1+ i) (1+ ilast)))]
(when (< [a j] amin) (set! amin [a (setv! imin j)])))
(vector-swap! a i imin))
a )
(define a #(9 8 2 6 3 5 4))
(sel-sort a)
→ #( 2 3 4 5 6 8 9)
Eiffel
class
SELECTION_SORT [G -> COMPARABLE]
feature {NONE}
index_of_min (ar: ARRAY [G]; lower: INTEGER): INTEGER
--Index of smallest element in 'ar' in the range of lower and the max index.
require
lower_positiv: lower >= 1
lower_in_range: lower <= ar.count
ar_not_void: ar /= Void
local
i: INTEGER
min: G
do
from
i := lower
min := ar.item (i)
Result := i
until
i + 1 > ar.count
loop
if ar.item (i + 1) < min then
min := ar.item (i + 1)
Result := i + 1
end
i := i + 1
end
ensure
result_is_set: Result /= Void
end
sort (ar: ARRAY [G]): ARRAY [G]
-- sort array ar with selectionsort
require
ar_not_void: ar /= Void
local
min_index: INTEGER
ith: G
do
create Result.make_empty
Result.deep_copy (ar)
across
Result as ic
loop
min_index := index_of_min (Result, ic.cursor_index)
ith := Result [ic.cursor_index]
Result [ic.cursor_index] := Result [min_index]
Result [min_index] := ith
end
ensure
Result_is_set: Result /= Void
Result_sorted: is_sorted (Result) = True
end
is_sorted (ar: ARRAY [G]): BOOLEAN
--- Is 'ar' sorted in ascending order?
require
ar_not_empty: ar.is_empty = False
local
i: INTEGER
do
Result := True
from
i := ar.lower
until
i = ar.upper
loop
if ar [i] > ar [i + 1] then
Result := False
end
i := i + 1
end
end
feature
selectionsort (ar: ARRAY [G]): ARRAY [G]
do
Result := sort (ar)
end
end
Test:
class
APPLICATION
create
make
feature
make
do
test := <<1, 27, 32, 99, 1, -7, 3, 5, 7>>
io.put_string ("Unsorted: ")
across
test as ic
loop
io.put_string (ic.item.out + " ")
end
create selectionsort
io.put_string ("%NSorted: ")
test := selectionsort.selectionsort (test)
across
test as ar
loop
io.put_string (ar.item.out + " ")
end
end
test: ARRAY [INTEGER]
selectionsort: SELECTION_SORT [INTEGER]
end
{{out}}
Unsorted: 1 27 32 99 1 -7 3 5 7
Sorted: -7 1 1 3 5 7 27 32 99
Elena
ELENA 4.1 :
import extensions;
import system'routines;
extension op
{
selectionSort()
{
var copy := self.clone();
for(int i := 0, i < copy.Length, i += 1)
{
int k := i;
for(int j := i + 1, j < copy.Length, j += 1)
{
if (copy[j] < copy[k])
{
k := j
}
};
copy.exchange(i,k)
};
^ copy
}
}
public program()
{
var list := new string[]::("this", "is", "a", "test", "of", "generic", "selection", "sort");
console.printLine("before:",list.asEnumerable());
console.printLine("after:",list.selectionSort().asEnumerable())
}
{{out}}
before:this,is,a,test,of,generic,selection,sort
after:a,generic,is,of,selection,sort,test,this
Elixir
defmodule Sort do
def selection_sort(list) when is_list(list), do: selection_sort(list, [])
defp selection_sort([], sorted), do: sorted
defp selection_sort(list, sorted) do
max = Enum.max(list)
selection_sort(List.delete(list, max), [max | sorted])
end
end
Example:
iex(10)> Sort.selection_sort([5,3,9,4,1,6,8,2,7])
[1, 2, 3, 4, 5, 6, 7, 8, 9]
Erlang
-module(solution).
-import(lists,[delete/2,max/1]).
-compile(export_all).
selection_sort([],Sort)-> Sort;
selection_sort(Ar,Sort)->
M=max(Ar),
Ad=delete(M,Ar),
selection_sort(Ad,[M|Sort]).
print_array([])->ok;
print_array([H|T])->
io:format("~p~n",[H]),
print_array(T).
main()->
Ans=selection_sort([1,5,7,8,4,10],[]),
print_array(Ans).
Euphoria
function selection_sort(sequence s)
object tmp
integer m
for i = 1 to length(s) do
m = i
for j = i+1 to length(s) do
if compare(s[j],s[m]) < 0 then
m = j
end if
end for
tmp = s[i]
s[i] = s[m]
s[m] = tmp
end for
return s
end function
include misc.e
constant s = {4, 15, "delta", 2, -31, 0, "alfa", 19, "gamma", 2, 13, "beta", 782, 1}
puts(1,"Before: ")
pretty_print(1,s,{2})
puts(1,"\nAfter: ")
pretty_print(1,selection_sort(s),{2})
{{out}}
Before: {
4,
15,
"delta",
2,
-31,
0,
"alfa",
19,
"gamma",
2,
13,
"beta",
782,
1
}
After: {
-31,
0,
1,
2,
2,
4,
13,
15,
19,
782,
"alfa",
"beta",
"delta",
"gamma"
}
=={{header|F Sharp|F#}}==
let rec ssort = function
[] -> []
| x::xs ->
let min, rest =
List.fold (fun (min,acc) x ->
if h<min then (h, min::acc)
else (min, h::acc))
(x, []) xs
in min::ssort rest
Factor
USING: kernel math sequences sequences.extras ;
: select ( m n seq -- )
[ dup ] 2dip [ <slice> [ ] infimum-by* drop over + ]
[ exchange ] bi ;
: selection-sort! ( seq -- seq' )
[ ] [ length dup ] [ ] tri [ select ] 2curry each-integer ;
Example use
IN: scratchpad { 5 -6 3 9 -2 4 -1 -6 5 -5 } selection-sort!
--- Data stack:
{ -6 -6 -5 -2 -1 3 4 5 5 9 }
Forth
defer less? ' < is less?
: least ( start end -- least )
over cell+ do
i @ over @ less? if drop i then
cell +loop ;
: selection ( array len -- )
cells over + tuck ( end start end )
cell- swap do ( end )
i over least ( end least )
i @ over @ i ! swap !
cell +loop drop ;
create array 8 , 1 , 4 , 2 , 10 , 3 , 7 , 9 , 6 , 5 ,
array 10 selection
array 10 cells dump
Fortran
{{works with|Fortran|95 and later}}
PROGRAM SELECTION
IMPLICIT NONE
INTEGER :: intArray(10) = (/ 4, 9, 3, -2, 0, 7, -5, 1, 6, 8 /)
WRITE(*,"(A,10I5)") "Unsorted array:", intArray
CALL Selection_sort(intArray)
WRITE(*,"(A,10I5)") "Sorted array :", intArray
CONTAINS
SUBROUTINE Selection_sort(a)
INTEGER, INTENT(IN OUT) :: a(:)
INTEGER :: i, minIndex, temp
DO i = 1, SIZE(a)-1
minIndex = MINLOC(a(i:), 1) + i - 1
IF (a(i) > a(minIndex)) THEN
temp = a(i)
a(i) = a(minIndex)
a(minIndex) = temp
END IF
END DO
END SUBROUTINE Selection_sort
END PROGRAM SELECTION
{{out}}
Unsorted array: 4 9 3 -2 0 7 -5 1 6 8
Sorted array : -5 -2 0 1 3 4 6 7 8 9
FreeBASIC
' version 03-12-2016
' compile with: fbc -s console
' for boundry checks on array's compile with: fbc -s console -exx
Sub selectionsort(arr() As Long)
' sort from lower bound to the highter bound
' array's can have subscript range from -2147483648 to +2147483647
Dim As Long i, j, x
Dim As Long lb = LBound(arr)
Dim As Long ub = UBound(arr)
For i = lb To ub -1
x = i
For j = i +1 To ub
If arr(j) < arr(x) Then x = j
Next
If x <> i Then
Swap arr(i), arr(x)
End If
Next
End Sub
' ------=< MAIN >=------
Dim As Long i, array(-7 To 7)
Dim As Long a = LBound(array), b = UBound(array)
Randomize Timer
For i = a To b : array(i) = i : Next
For i = a To b ' little shuffle
Swap array(i), array(Int(Rnd * (b - a +1)) + a)
Next
Print "unsort ";
For i = a To b : Print Using "####"; array(i); : Next : Print
selectionsort(array()) ' sort the array
Print " sort ";
For i = a To b : Print Using "####"; array(i); : Next : Print
' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End
{{out}}
unsort 1 -7 -5 -4 6 5 -3 4 2 0 3 -6 -2 7 -1
sort -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7
Gambas
siLow As Short = -99 'Set the lowest value number to create
siHigh As Short = 99 'Set the highest value number to create
siQty As Short = 20 'Set the quantity of numbers to create
Public Sub Main()
Dim siToSort As Short[] = CreateNumbersToSort()
Dim siPos, siLow, siChar, siCount As Short
PrintOut("To sort: ", siToSort)
For siCount = 0 To siToSort.Max
siChar = siCount
For siPos = siCount + 1 To siToSort.Max
If siToSort[siChar] > siToSort[siPos] Then siChar = siPos
Next
siLow = siToSort[siChar]
siToSort.Delete(siChar, 1)
siToSort.Add(siLow, siCount)
Next
PrintOut(" Sorted: ", siToSort)
End
'---------------------------------------------------------
Public Sub PrintOut(sText As String, siToSort As String[])
Dim siCount As Short
Print sText;
For siCount = 0 To siToSort.Max
Print siToSort[siCount];
If siCount <> siToSort.max Then Print ", ";
Next
Print
End
'---------------------------------------------------------
Public Sub CreateNumbersToSort() As Short[]
Dim siCount As Short
Dim siList As New Short[]
For siCount = 0 To siQty
siList.Add(Rand(siLow, siHigh))
Next
Return siList
End
Output:
To sort: -11, -64, -20, -84, 94, -60, -82, -82, 37, -30, -75, 73, 19, -97, 81, -26, 55, 8, -15, -31, 36
Sorted: -97, -84, -82, -82, -75, -64, -60, -31, -30, -26, -20, -15, -11, 8, 19, 36, 37, 55, 73, 81, 94
GAP
SelectionSort := function(v)
local i, j, k, n, m;
n := Size(v);
for i in [1 .. n] do
k := i;
m := v[i];
for j in [i + 1 .. n] do
if v[j] < m then
k := j;
m := v[j];
fi;
od;
v[k] := v[i];
v[i] := m;
od;
end;
v := List([1 .. 100], n -> Random([1 .. 100]));
SelectionSort(v);
v;
Go
package main
import "fmt"
var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
func main() {
fmt.Println("before:", a)
selectionSort(a)
fmt.Println("after: ", a)
}
func selectionSort(a []int) {
last := len(a) - 1
for i := 0; i < last; i++ {
aMin := a[i]
iMin := i
for j := i + 1; j < len(a); j++ {
if a[j] < aMin {
aMin = a[j]
iMin = j
}
}
a[i], a[iMin] = aMin, a[i]
}
}
More generic version that sorts anything that implements sort.Interface:
package main
import (
"sort"
"fmt"
)
var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
func main() {
fmt.Println("before:", a)
selectionSort(sort.IntSlice(a))
fmt.Println("after: ", a)
}
func selectionSort(a sort.Interface) {
last := a.Len() - 1
for i := 0; i < last; i++ {
iMin := i
for j := i + 1; j < a.Len(); j++ {
if a.Less(j, iMin) {
iMin = j
}
}
a.Swap(i, iMin)
}
}
Haskell
import Data.List (delete)
selSort :: (Ord a) => [a] -> [a]
selSort [] = []
selSort xs = selSort (delete x xs) ++ [x]
where x = maximum xs
Haxe
static function selectionSort(arr:Array<Int>) {
var len = arr.length;
for (index in 0...len)
{
var minIndex = index;
for (remainingIndex in (index+1)...len)
{
if (arr[minIndex] > arr[remainingIndex]) {
minIndex = remainingIndex;
}
}
if (index != minIndex) {
var temp = arr[index];
arr[index] = arr[minIndex];
arr[minIndex] = temp;
}
}
}
Io
List do (
selectionSortInPlace := method(
size repeat(idx,
swapIndices(idx, indexOf(slice(idx, size) min))
)
)
)
l := list(-1, 4, 2, -9)
l selectionSortInPlace println # ==> list(-9, -1, 2, 4)
=={{header|Icon}} and {{header|Unicon}}==
procedure main() #: demonstrate various ways to sort a list and string
demosort(selectionsort,[3, 14, 1, 5, 9, 2, 6, 3],"qwerty")
end
procedure selectionsort(X,op) #: return sorted list ascending(or descending)
local i,m
op := sortop(op,X) # select how and what we sort
every i := 1 to *X-1 do {
m := i
every j := i + 1 to *X do
if op(X[j],X[m]) then m := j # find X that belongs @i low (or high)
X[m ~= i] :=: X[m]
}
return X
end
Note: This example relies on [[Sorting_algorithms/Bubble_sort#Icon| the supporting procedures 'sortop', and 'demosort' in Bubble Sort]]. The full demosort exercises the named sort of a list with op = "numeric", "string", ">>" (lexically gt, descending),">" (numerically gt, descending), a custom comparator, and also a string.
{{out}} Abbreviated sample
Sorting Demo using procedure selectionsort
on list : [ 3 14 1 5 9 2 6 3 ]
with op = &null: [ 1 2 3 3 5 6 9 14 ] (0 ms)
...
on string : "qwerty"
with op = &null: "eqrtwy" (0 ms)
=={{header|IS-BASIC}}==
## J
{{eff note|J|/:~}}
Create the following script and load it to a J session.
```j
selectionSort=: verb define
data=. y
for_xyz. y do.
temp=. xyz_index }. data
nvidx=. xyz_index + temp i. <./ temp
data=. ((xyz_index, nvidx) { data) (nvidx, xyz_index) } data
end.
data
)
In an email discussion, Roger_Hui presented the following tacit code:
ix=: C.~ <@~.@(0, (i. <./))
ss1=: ({. , $:@}.)@ix^:(*@#)
To validate:
[data=. 6 15 19 12 14 19 0 17 0 14
6 15 19 12 14 19 0 17 0 14
selectionSort data
0 0 6 12 14 14 15 17 19 19
ss1 data
0 0 6 12 14 14 15 17 19 19
Java
This algorithm sorts in place. The call sort(array) will rearrange the array and not create a new one.
public static void sort(int[] nums){
for(int currentPlace = 0;currentPlace<nums.length-1;currentPlace++){
int smallest = Integer.MAX_VALUE;
int smallestAt = currentPlace+1;
for(int check = currentPlace; check<nums.length;check++){
if(nums[check]<smallest){
smallestAt = check;
smallest = nums[check];
}
}
int temp = nums[currentPlace];
nums[currentPlace] = nums[smallestAt];
nums[smallestAt] = temp;
}
}
JavaScript
This algorithm sorts array of numbers.
function selectionSort(nums) {
var len = nums.length;
for(var i = 0; i < len; i++) {
var minAt = i;
for(var j = i + 1; j < len; j++) {
if(nums[j] < nums[minAt])
minAt = j;
}
if(minAt != i) {
var temp = nums[i];
nums[i] = nums[minAt];
nums[minAt] = temp;
}
}
return nums;
}
jq
The following implementation does not impose any restrictions on the types of entities that may appear in the array to be sorted. That is, the array may include any collection of JSON entities.
The definition also illustrates the use of an inner function (swap), and the use of jq's reduction operator, reduce.
# Sort any array
def selection_sort:
def swap(i;j): if i == j then . else .[i] as $tmp | .[i] = .[j] | .[j] = $tmp end;
length as $length
| reduce range(0; $length) as $currentPlace
# state: $array
( .;
. as $array
| (reduce range( $currentPlace; $length) as $check
# state: [ smallestAt, smallest] except initially [null]
( [$currentPlace+1] ;
if length == 1 or $array[$check] < .[1]
then [$check, $array[$check] ]
else .
end
)) as $ans
| swap( $currentPlace; $ans[0] )
) ;
Example:
[1, 3.3, null, 2, null, [1,{"a":1 }] ] | selection_sort
{{Out}}
[
null,
null,
1,
2,
3.3,
[
1,
{
"a": 1
}
]
]
Julia
{{works with|Julia|0.6}}
function selectionsort!(arr::Vector{<:Real})
len = length(arr)
if len < 2 return arr end
for i in 1:len-1
lmin, j = findmin(arr[i+1:end])
if lmin < arr[i]
arr[i+j] = arr[i]
arr[i] = lmin
end
end
return arr
end
v = rand(-10:10, 10)
println("# unordered: $v\n -> ordered: ", selectionsort!(v))
{{out}}
# unordered: [2, -10, 0, -10, -9, -3, -3, 7, 8, -3]
-> ordered: [-10, -10, -9, -3, -3, -3, 0, 2, 7, 8]
Kotlin
{{trans|C#}}
.selection_sort() {
for (i in 0..size - 2) {
var k = i
for (j in i + 1..size - 1)
if (this[j] < this[k])
k = j
if (k != i) {
val tmp = this[i]
this[i] = this[k]
this[k] = tmp
}
}
}
fun main(args: Array<String>) {
val i = arrayOf(4, 9, 3, -2, 0, 7, -5, 1, 6, 8)
i.selection_sort()
println(i.joinToString())
val s = Array(i.size, { -i[it].toShort() })
s.selection_sort()
println(s.joinToString())
val c = arrayOf('z', 'h', 'd', 'c', 'a')
c.selection_sort()
println(c.joinToString())
}
{{out}}
-5, -2, 0, 1, 3, 4, 6, 7, 8, 9
-9, -8, -7, -6, -4, -3, -1, 0, 2, 5
a, c, d, h, z
Liberty BASIC
itemCount = 20
dim A(itemCount)
for i = 1 to itemCount
A(i) = int(rnd(1) * 100)
next i
print "Before Sort"
gosub [printArray]
'--- Selection sort algorithm
for i = 1 to itemCount-1
jMin = i
for j = i+1 to itemCount
if A(j) < A(jMin) then jMin = j
next
tmp = A(i)
A(i) = A(jMin)
A(jMin) = tmp
next
'--- end of (Selection sort algorithm)
print "After Sort"
gosub [printArray]
end
[printArray]
for i = 1 to itemCount
print using("###", A(i));
next i
print
return
Lua
function SelectionSort( f )
for k = 1, #f-1 do
local idx = k
for i = k+1, #f do
if f[i] < f[idx] then
idx = i
end
end
f[k], f[idx] = f[idx], f[k]
end
end
f = { 15, -3, 0, -1, 5, 4, 5, 20, -8 }
SelectionSort( f )
for i in next, f do
print( f[i] )
end
Maple
arr:= Array([17,3,72,0,36,2,3,8,40,0]):
len := numelems(arr):
for i to len-1 do
j_min := i:
for j from i+1 to len do
if arr[j] < arr[j_min] then
j_min := j:
end if:
end do:
if (not j_min = i) then
temp := arr[i]:
arr[i] := arr[j_min]:
arr[j_min] := temp:
end if:
end do:
arr;
{{Out|Output}}
[0,0,2,3,3,8,17,36,40,72]
Mathematica
Procedural solution with custom min function:
SelectSort[x_List] := Module[{n = 1, temp, xi = x, j},
While[n <= Length@x,
temp = xi[[n]];
For[j = n, j <= Length@x, j++,
If[xi[[j]] < temp, temp = xi[[j]]];
];
xi[[n ;;]] = {temp}~Join~
Delete[xi[[n ;;]], First@Position[xi[[n ;;]], temp] ];
n++;
];
xi
]
Recursive solution using a pre-existing Min[] function:
SelectSort2[x_List]:= Flatten[{Min@x, If[Length@x > 1, SelectSort2@Drop[x, First@Position[x, Min@x]], {}] }];
Validate by testing the ordering of a random number of randomly-sized random lists:
{And @@ Table[l = RandomInteger[150, RandomInteger[1000]];
Through[And[Length@# == Length@SelectSort@# &, OrderedQ@SelectSort@# &]@l],
{RandomInteger[150]}],
Block[{$RecursionLimit = Infinity},
And @@ Table[l = RandomInteger[150, RandomInteger[1000]];
Through[And[Length@# == Length@SelectSort2@# &, OrderedQ@SelectSort2@# &]@l],
{RandomInteger[150]}]
]}
Validation Result:
{True, True}
=={{header|MATLAB}} / {{header|Octave}}==
function list = selectionSort(list)
listSize = numel(list);
for i = (1:listSize-1)
minElem = list(i);
minIndex = i;
%This for loop can be vectorized, but there will be no significant
%increase in sorting efficiency.
for j = (i:listSize)
if list(j) <= minElem
minElem = list(j);
minIndex = j;
end
end
if i ~= minIndex
list([minIndex i]) = list([i minIndex]); %Swap
end
end %for
end %selectionSort
Sample Usage:
selectionSort([4 3 1 5 6 2])
ans =
1 2 3 4 5 6
Maxima
selection_sort(v) := block([k, m, n],
n: length(v),
for i: 1 thru n do (
k: i,
m: v[i],
for j: i + 1 thru n do
if v[j] < m then (k: j, m: v[j]),
v[k]: v[i],
v[i]: m
))$
v: makelist(random(199) - 99, i, 1, 10); /* [52, -85, 41, -70, -59, 88, 19, 80, 90, 44] */
selection_sort(v)$
v; /* [-85, -70, -59, 19, 41, 44, 52, 80, 88, 90] */
MAXScript
fn selectionSort arr =
(
local min = undefined
for i in 1 to arr.count do
(
min = i
for j in i+1 to arr.count do
(
if arr[j] < arr[min] then
(
min = j
)
)
swap arr[i] arr[min]
)
arr
)
data = selectionSort #(4, 9, 3, -2, 0, 7, -5, 1, 6, 8)
print data
N/t/roff
.de end
..
.de array
. nr \\$1.c 0 1
. de \\$1.push end
. nr \\$1..\\\\n+[\\$1.c] \\\\$1
. end
. de \\$1.pushln end
. if \\\\n(.$>0 .\\$1.push \\\\$1
. if \\\\n(.$>1 \{ \
. shift
. \\$1.pushln \\\\$@
. \}
. end
. de \\$1.dump end
. nr i 0 1
. while \\\\n+i<=\\\\n[\\$1.c] .tm \\\\n[\\$1..\\\\ni]
. rr i
. end
. de \\$1.swap end
. if (\\\\$1<=\\\\n[\\$1.c])&(\\\\$2<=\\\\n[\\$1.c]) \{ \
. nr b \\\\n[\\$1..\\\\$1]
. nr \\$1..\\\\$1 \\\\n[\\$1..\\\\$2]
. nr \\$1..\\\\$2 \\\\nb
. rr b
. \}
. end
..
.array myArray
.myArray.pushln 14 62 483 21 12 11 0 589 212 10 5 4 95 4 2 2 12 0 0
.de sort
. nr i 0 1
. while \\n+i<=\\n[\\$1.c] \{ \
. nr j \\ni 1
. nr st \\nj
. while \\n+j<=\\n[\\$1.c] \{ \
. if \\n[\\$1..\\nj]<\\n[\\$1..\\n(st] .nr st \\nj
. \}
. if !\\n(st=\\ni .\\$1.swap \\ni \\n(st
. \}
..
.sort myArray
.myArray.dump
Output
## Nemerle
{{trans|C#}}
```Nemerle
using System;
using System.Console;
module Selection
{
public static Sort[T](this a : array[T]) : void
where T : IComparable
{
mutable k = 0;
def lastindex = a.Length - 1;
foreach (i in [0 .. lastindex])
{
k = i;
foreach (j in [i .. lastindex])
when (a[j].CompareTo(a[k]) < 0) k = j;
a[i] <-> a[k];
}
}
Main() : void
{
def arr = array[6, 2, 8, 3, 9, 4, 7, 3, 9, 1];
arr.Sort();
foreach (i in arr) Write($"$i ");
}
}
NetRexx
/* NetRexx */
options replace format comments java crossref savelog symbols binary
import java.util.List
placesList = [String -
"UK London", "US New York", "US Boston", "US Washington" -
, "UK Washington", "US Birmingham", "UK Birmingham", "UK Boston" -
]
lists = [ -
placesList -
, selectionSort(String[] Arrays.copyOf(placesList, placesList.length)) -
]
loop ln = 0 to lists.length - 1
cl = lists[ln]
loop ct = 0 to cl.length - 1
say cl[ct]
end ct
say
end ln
return
method selectionSort(a = String[]) public constant binary returns String[]
rl = String[a.length]
al = List selectionSort(Arrays.asList(a))
al.toArray(rl)
return rl
method selectionSort(a = List) public constant binary returns ArrayList
ra = ArrayList(a)
n = ra.size
iPos = int
iMin = int
loop iPos = 0 to n - 1
iMin = iPos
loop i_ = iPos + 1 to n - 1
if (Comparable ra.get(i_)).compareTo(Comparable ra.get(iMin)) < 0 then do
iMin = i_
end
end i_
if iMin \= iPos then do
swap = ra.get(iPos)
ra.set(iPos, ra.get(iMin))
ra.set(iMin, swap)
end
end iPos
return ra
{{out}}
UK London
US New York
US Boston
US Washington
UK Washington
US Birmingham
UK Birmingham
UK Boston
UK Birmingham
UK Boston
UK London
UK Washington
US Birmingham
US Boston
US New York
US Washington
Nim
proc selectionSort[T](a: var openarray[T]) =
let n = a.len
for i in 0 .. <n:
var m = i
for j in i .. <n:
if a[j] < a[m]:
m = j
swap a[i], a[m]
var a = @[4, 65, 2, -31, 0, 99, 2, 83, 782]
selectionSort a
echo a
{{out}}
@[-31, 0, 2, 2, 4, 65, 83, 99, 782]
OCaml
let rec selection_sort = function
[] -> []
| first::lst ->
let rec select_r small output = function
[] -> small :: selection_sort output
| x::xs when x < small -> select_r x (small::output) xs
| x::xs -> select_r small (x::output) xs
in
select_r first [] lst
Oforth
: selectSort(l)
| b j i k s |
l size ->s
l asListBuffer ->b
s loop: i [
i dup ->k b at
i 1 + s for: j [ b at(j) 2dup <= ifTrue: [ drop ] else: [ nip j ->k ] ]
k i b at b put i swap b put
]
b dup freeze ;
ooRexx
/*REXX ****************************************************************
* program sorts an array using the selection-sort method.
* derived from REXX solution
* Note that ooRexx can process Elements of the stem argument (Use Arg)
* 06.10.2010 Walter Pachl
**********************************************************************/
call generate /*generate the array elements. */
call show 'before sort' /*show the before array elements,*/
call selectionSort x. /*invoke the selection sort. */
call show 'after sort' /*show the after array elements.*/
exit /*stick a fork in it, we're done.*/
selectionSort: Procedure
Use Arg s. /* gain access to the argument */
do j=1 To s.0-1
t=s.j;
p=j;
do k=j+1 to s.0
if s.k<t then do;
t=s.k;
p=k;
end
end
if p=j then
iterate
t=s.j;
s.j=s.p;
s.p=t
end
return
show:
Parse Arg heading
Say heading
Do i=1 To x.0
Say i' 'x.i
End
say copies('-',79)
Return
return
generate:
x.1='---The seven hills of Rome:---'
x.2='
### ========================
'
x.3='Caelian'
x.4='Palatine'
x.5='Capitoline'
x.6='Virminal'
x.7='Esquiline'
x.8='Quirinal'
x.9='Aventine'
x.0=9
return
Oz
Although lists are much more used in Oz than arrays, this algorithm seems more natural for arrays.
declare
proc {SelectionSort Arr}
proc {Swap K L}
Arr.K := (Arr.L := Arr.K)
end
Low = {Array.low Arr}
High = {Array.high Arr}
in
%% for every index I of the array
for I in Low..High do
%% find the index of the minimum element
%% with an index >= I
Min = {NewCell Arr.I}
MinIndex = {NewCell I}
in
for J in I..High do
if Arr.J < @Min then
Min := Arr.J
MinIndex := J
end
end
%% and put that minimum element to the left
{Swap @MinIndex I}
end
end
A = {Tuple.toArray unit(3 1 4 1 5 9 2 6 5)}
in
{SelectionSort A}
{Show {Array.toRecord unit A}}
PARI/GP
selectionSort(v)={
for(i=1,#v-1,
my(mn=i,t);
for(j=i+1,#v,
if(v[j]<v[mn],mn=j)
);
t=v[mn];
v[mn]=v[i];
v[i]=t
);
v
};
Pascal
See [[Sorting_algorithms/Selection_sort#Delphi | Delphi]]
Perl
{{trans|Tcl}}
sub selection_sort
{my @a = @_;
foreach my $i (0 .. $#a - 1)
{my $min = $i + 1;
$a[$_] < $a[$min] and $min = $_ foreach $min .. $#a;
$a[$i] > $a[$min] and @a[$i, $min] = @a[$min, $i];}
return @a;}
Perl 6
Solution 1:
sub selection_sort ( @a is copy ) {
for 0 ..^ @a.end -> $i {
my $min = [ $i+1 .. @a.end ].min: { @a[$_] };
@a[$i, $min] = @a[$min, $i] if @a[$i] > @a[$min];
}
return @a;
}
my @data = 22, 7, 2, -5, 8, 4;
say 'input = ' ~ @data;
say 'output = ' ~ @data.&selection_sort;
{{out}}
input = 22 7 2 -5 8 4
output = -5 2 4 7 8 22
Solution 2:
sub selectionSort(@tmp) {
for ^@tmp -> $i {
my $min = $i; @tmp[$i, $_] = @tmp[$_, $i] if @tmp[$min] > @tmp[$_] for $i^..^@tmp;
}
return @tmp;
}
{{out}}
input = 22 7 2 -5 8 4
output = -5 2 4 7 8 22
Phix
Copy of [[Sorting_algorithms/Selection_sort#Euphoria|Euphoria]]
function selection_sort(sequence s)
integer m
for i=1 to length(s) do
m = i
for j=i+1 to length(s) do
if s[j]<s[m] then
m = j
end if
end for
{s[i],s[m]} = {s[m],s[i]}
end for
return s
end function
PHP
Iterative:
function selection_sort(&$arr) {
$n = count($arr);
for($i = 0; $i < count($arr); $i++) {
$min = $i;
for($j = $i + 1; $j < $n; $j++){
if($arr[$j] < $arr[$min]){
$min = $j;
}
}
list($arr[$i],$arr[$min]) = array($arr[$min],$arr[$i]);
}
}
Recursive:
function selectionsort($arr,$result=array()){
if(count($arr) == 0){
return $result;
}
$nresult = $result;
$nresult[] = min($arr);
unset($arr[array_search(min($arr),$arr)]);
return selectionsort($arr,$nresult);
}
PicoLisp
(de selectionSort (Lst)
(map
'((L) (and (cdr L) (xchg L (member (apply min @) L))))
Lst )
Lst )
PL/I
Selection: procedure options (main); /* 2 November 2013 */
declare a(10) fixed binary initial (
5, 7, 3, 98, 4, -3, 25, 20, 60, 17);
put edit (trim(a)) (a, x(1));
call Selection_Sort (a);
put skip edit (trim(a)) (a, x(1));
Selection_sort: procedure (a);
declare a(*) fixed binary;
declare t fixed binary;
declare n fixed binary;
declare (i, j, k) fixed binary;
n = hbound(a,1);
do j = 1 to n;
k = j; t = a(j);
do i = j+1 to n;
if t > a(i) then do; t = a(i); k = i; end;
end;
a(k) = a(j); a(j) = t;
end;
end Selection_Sort;
end Selection;
Results:
5 7 3 98 4 -3 25 20 60 17
-3 3 4 5 7 17 20 25 60 98
PowerShell
Function SelectionSort( [Array] $data )
{
$datal=$data.length-1
0..( $datal - 1 ) | ForEach-Object {
$min = $data[ $_ ]
$mini = $_
( $_ + 1 )..$datal | ForEach-Object {
if( $data[ $_ ] -lt $min ) {
$min = $data[ $_ ]
$mini = $_
}
}
$temp = $data[ $_ ]
$data[ $_ ] = $min
$data[ $mini ] = $temp
}
$data
}
$l = 100; SelectionSort( ( 1..$l | ForEach-Object { $Rand = New-Object Random }{ $Rand.Next( 0, $l - 1 ) } ) )
Prolog
Works with '''SWI-Prolog 6.3.11''' (needs nth0/4).
selection_sort([], []).
selection_sort([H | L], [H1 | L2]) :-
exchange(H, L, H1, L1),
selection_sort(L1, L2).
exchange(H, [], H, []).
exchange(H, L, H1, L1) :-
min_list(L, H2),
( H < H2
-> H1 = H, L1 = L
; H1 = H2,
% does the exchange of the number H
% and the min of the list
nth0(Ind, L, H1, L2),
nth0(Ind, L1, H, L2)).
PureBasic
Procedure selectionSort(Array a(1))
Protected i, j, lastIndex, minIndex
lastIndex = ArraySize(a())
For i = 0 To lastIndex - 1
minIndex = i
For j = i + 1 To lastIndex
If a(minIndex) > a(j)
minIndex = j
EndIf
Next
Swap a(minIndex), a(i)
Next
EndProcedure
Python
def selection_sort(lst):
for i, e in enumerate(lst):
mn = min(range(i,len(lst)), key=lst.__getitem__)
lst[i], lst[mn] = lst[mn], e
return lst
R
For loop:
selectionsort.loop <- function(x)
{
lenx <- length(x)
for(i in seq_along(x))
{
mini <- (i - 1) + which.min(x[i:lenx])
start_ <- seq_len(i-1)
x <- c(x[start_], x[mini], x[-c(start_, mini)])
}
x
}
Recursive:
(A prettier solution, but, you may need to increase the value of options("expressions") to test it. Also, you may get a stack overflow if the length of the input vector is more than a few thousand.)
selectionsort.rec <- function(x)
{
if(length(x) > 1)
{
mini <- which.min(x)
c(x[mini], selectionsort(x[-mini]))
} else x
}
Qi
{{trans|sml}}
(define select-r
Small [] Output -> [Small | (selection-sort Output)]
Small [X|Xs] Output -> (select-r X Xs [Small|Output]) where (< X Small)
Small [X|Xs] Output -> (select-r Small Xs [X|Output]))
(define selection-sort
[] -> []
[First|Lst] -> (select-r First Lst []))
(selection-sort [8 7 4 3 2 0 9 1 5 6])
Racket
#lang racket
(define (selection-sort xs)
(cond [(empty? xs) '()]
[else (define x0 (apply min xs))
(cons x0 (selection-sort (remove x0 xs)))]))
Ra
class SelectionSort
**Sort a list with the Selection Sort algorithm**
on start
args := program arguments
.sort(args)
print args
define sort(list) is shared
**Sort the list**
test
list := [4, 2, 7, 3]
.sort(list)
assert list = [2, 3, 4, 7]
body
count := list.count
last := count - 1
for i in last
minCandidate := i
j := i + 1
while j < count
if list[j] < list[minCandidate], minCandidate := j
j :+ 1
temp := list[i]
list[i] := list[minCandidate]
list[minCandidate] := temp
REXX
/*REXX program sorts a stemmed array using the selection─sort algorithm. */
@.=; @.1 = '---The seven hills of Rome:---'
@.2 = '
### ========================
'; @.6 = 'Virminal'
@.3 = 'Caelian' ; @.7 = 'Esquiline'
@.4 = 'Palatine' ; @.8 = 'Quirinal'
@.5 = 'Capitoline' ; @.9 = 'Aventine'
do #=1 until @.#==''; end /*find the number of items in the array*/
# = # - 1 /*adjust # (because of DO index). */
call show 'before sort' /*show the before array elements. */
say copies('▒', 65) /*show a nice separator line (fence). */
call selectionSort # /*invoke selection sort (and # items). */
call show ' after sort' /*show the after array elements. */
exit /*stick a fork in it, we're a;; done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
selectionSort: procedure expose @.; parse arg n
do j=1 for n-1; _= @.j; p= j
do k=j+1 to n; if @.k>=_ then iterate
_= @.k; p= k /*this item is out─of─order, swap later*/
end /*k*/
if p==j then iterate /*if the same, the order of items is OK*/
_= @.j; @.j= @.p; @.p= _ /*swap 2 items that're out─of─sequence.*/
end /*j*/
return
/*──────────────────────────────────────────────────────────────────────────────────────*/
show: do i=1 for #; say ' element' right(i,length(#)) arg(1)":" @.i; end; return
{{out|output|:}}
element 1 before sort: ---The seven hills of Rome:---
element 2 before sort:
### ========================
element 3 before sort: Caelian
element 4 before sort: Palatine
element 5 before sort: Capitoline
element 6 before sort: Virminal
element 7 before sort: Esquiline
element 8 before sort: Quirinal
element 9 before sort: Aventine
▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒
element 1 after sort: ---The seven hills of Rome:---
element 2 after sort:
### ========================
element 3 after sort: Aventine
element 4 after sort: Caelian
element 5 after sort: Capitoline
element 6 after sort: Esquiline
element 7 after sort: Palatine
element 8 after sort: Quirinal
element 9 after sort: Virminal
Ring
aList = [7,6,5,9,8,4,3,1,2,0]
see sortList(aList)
func sortList list
count = len(list) + 1
last = count - 1
for i = 1 to last
minCandidate = i
j = i + 1
while j < count
if list[j] < list[minCandidate] minCandidate = j ok
j = j + 1
end
temp = list[i]
list[i] = list[minCandidate]
list[minCandidate] = temp
next
return list
Ruby
{{trans|Tcl}}
class Array
def selectionsort!
for i in 0..length-2
min_idx = i
for j in (i+1)...length
min_idx = j if self[j] < self[min_idx]
end
self[i], self[min_idx] = self[min_idx], self[i]
end
self
end
end
ary = [7,6,5,9,8,4,3,1,2,0]
p ary.selectionsort!
# => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
Run BASIC
siz = 10
dim srdData(siz)
for i = 1 to siz
srtData(i) = rnd(0) * 100
next i
FOR i = 1 TO siz-1
lo = i
FOR j = (i + 1) TO siz
IF srtData(j) < srtData(lo) lo = j
NEXT j
if i <> lo then
temp = srtData(i)
srtData(i) = srtData(lo)
srtData(lo) = temp
end if
NEXT i
for i = 1 to siz
print i;chr$(9);srtData(i)
next i
1 20.5576419
2 32.4299311
3 48.345375
4 54.135847
5 63.1427764
6 67.8079128
7 85.2134895
8 91.3576602
9 95.4280853
10 98.8323211
Rust
fn selection_sort(array: &mut [i32]) {
let mut min;
for i in 0..array.len() {
min = i;
for j in (i+1)..array.len() {
if array[j] < array[min] {
min = j;
}
}
let tmp = array[i];
array[i] = array[min];
array[min] = tmp;
}
}
fn main() {
let mut array = [ 9, 4, 8, 3, -5, 2, 1, 6 ];
println!("The initial array is {:?}", array);
selection_sort(&mut array);
println!(" The sorted array is {:?}", array);
}
Scala
def swap(a: Array[Int], i1: Int, i2: Int) = { val tmp = a(i1); a(i1) = a(i2); a(i2) = tmp }
def selectionSort(a: Array[Int]) =
for (i <- 0 until a.size - 1)
swap(a, i, (i + 1 until a.size).foldLeft(i)((currMin, index) =>
if (a(index) < a(currMin)) index else currMin))
This version avoids the extra definition by using a function literal:
def selectionSort(a: Array[Int]) = for (i <- 0 until a.size - 1) (
{ (i1: Int, i2: Int) => val tmp = a(i1); a(i1) = a(i2); a(i2) = tmp }
) (i, (i + 1 until a.size).foldLeft(i)((currMin, index) => if (a(index) < a(currMin)) index else currMin) )
Functional way:
def selectionSort[T <% Ordered[T]](list: List[T]): List[T] = {
def remove(e: T, list: List[T]): List[T] =
list match {
case Nil => Nil
case x :: xs if x == e => xs
case x :: xs => x :: remove(e, xs)
}
list match {
case Nil => Nil
case _ =>
val min = list.min
min :: selectionSort(remove(min, list))
}
}
Seed7
const proc: selectionSort (inout array elemType: arr) is func
local
var integer: i is 0;
var integer: j is 0;
var integer: min is 0;
var elemType: help is elemType.value;
begin
for i range 1 to length(arr) - 1 do
min := i;
for j range i + 1 to length(arr) do
if arr[j] < arr[min] then
min := j;
end if;
end for;
help := arr[min];
arr[min] := arr[i];
arr[i] := help;
end for;
end func;
Original source: [http://seed7.sourceforge.net/algorith/sorting.htm#selectionSort]
Sidef
{{trans|Ruby}}
class Array {
method selectionsort {
for i in ^(self.end) {
var min_idx = i
for j in (i+1 .. self.end) {
if (self[j] < self[min_idx]) {
min_idx = j
}
}
self.swap(i, min_idx)
}
return self
}
}
var nums = [7,6,5,9,8,4,3,1,2,0];
say nums.selectionsort;
var strs = ["John", "Kate", "Zerg", "Alice", "Joe", "Jane"];
say strs.selectionsort;
Standard ML
fun selection_sort [] = []
| selection_sort (first::lst) =
let
val (small, output) = foldl
(fn (x, (small, output)) =>
if x < small then
(x, small::output)
else
(small, x::output)
) (first, []) lst
in
small :: selection_sort output
end
Stata
mata
function selection_sort(real vector a) {
real scalar i, j, k, n
n = length(a)
for (i = 1; i < n; i++) {
k = i
for (j = i+1; j <= n; j++) {
if (a[j] < a[k]) k = j
}
if (k != i) a[(i, k)] = a[(k, i)]
}
}
end
Swift
func selectionSort(inout arr:[Int]) {
var min:Int
for n in 0..<arr.count {
min = n
for x in n+1..<arr.count {
if (arr[x] < arr[min]) {
min = x
}
}
if min != n {
let temp = arr[min]
arr[min] = arr[n]
arr[n] = temp
}
}
}
Tcl
{{tcllib|struct::list}}
package require Tcl 8.5
package require struct::list
proc selectionsort {A} {
set len [llength $A]
for {set i 0} {$i < $len - 1} {incr i} {
set min_idx [expr {$i + 1}]
for {set j $min_idx} {$j < $len} {incr j} {
if {[lindex $A $j] < [lindex $A $min_idx]} {
set min_idx $j
}
}
if {[lindex $A $i] > [lindex $A $min_idx]} {
struct::list swap A $i $min_idx
}
}
return $A
}
puts [selectionsort {8 6 4 2 1 3 5 7 9}] ;# => 1 2 3 4 5 6 7 8 9
=={{header|TI-83 BASIC}}== Store input into L1 and prgmSORTSLCT will store the sorted output into L2. :L1→L2 :dim(L2)→I :For(A,1,I) :A→C :0→X :For(B,A,I) :If L2(B)<L2(C) :Then :B→C :1→X :End :End :If X=1 :Then :L2(C)→B :L2(A)→L2(C) :B→L2(A) :End :End :DelVar A :DelVar B :DelVar C :DelVar I :DelVar X :Return
uBasic/4tH
END
_Selectionsort PARAM (1) ' Selection sort LOCAL (3)
FOR b@ = 0 TO a@-1 c@ = b@
FOR d@ = b@ TO a@-1
IF @(d@) < @(c@) THEN c@ = d@
NEXT
IF b@ # c@ THEN PROC _Swap (b@, c@)
NEXT RETURN
_Swap PARAM(2) ' Swap two array elements PUSH @(a@) @(a@) = @(b@) @(b@) = POP() RETURN
_InitArray ' Init example array PUSH 4, 65, 2, -31, 0, 99, 2, 83, 782, 1
FOR i = 0 TO 9 @(i) = POP() NEXT
RETURN (i)
_ShowArray PARAM (1) ' Show array subroutine FOR i = 0 TO a@-1 PRINT @(i), NEXT
PRINT RETURN
## Ursala
The selection_sort function is parameterized by a relational predicate p.
There are no arrays in Ursala so it uses a list, and the selected item
is deleted from the list and inserted into another on each iteration
rather than swapped with a preceding item of the same list.
```Ursala
#import std
selection_sort "p" = @iNX ~&l->rx ^(gldif ==,~&r)^/~&l ^|C/"p"$- ~&
This is already a bad way to code a sorting algorithm in this language, but with only a bit more work, we can get a bigger and slower version that more closely simulates the operations of repeatedly reordering an array.
selection_sort "p" = ~&itB^?a\~&a ^|JahPfatPRC/~& ~=-~BrhPltPClhPrtPCTlrTQrS^D/"p"$- ~&
Here is a test program sorting by the partial order relation on natural numbers.
#import nat
#cast %nL
example = selection_sort(nleq) <294,263,240,473,596,392,621,348,220,815>
{{out}}
<220,240,263,294,348,392,473,596,621,815>
VBA
I shameless stole the swap function from the bubblesort VBscript implementation.
sub swap( byref a, byref b)
dim tmp
tmp = a
a = b
b = tmp
end sub
function selectionSort (a)
for i = 0 to ubound(a)
k = i
for j=i+1 to ubound(a)
if a(j) < a(i) then
swap a(i), a(j)
end if
next
next
selectionSort = a
end function
VBScript
Function Selection_Sort(s)
arr = Split(s,",")
For i = 0 To UBound(arr)
For j = i To UBound(arr)
temp = arr(i)
If arr(j) < arr(i) Then
arr(i) = arr(j)
arr(j) = temp
End If
Next
Next
Selection_Sort = (Join(arr,","))
End Function
WScript.StdOut.Write "Pre-Sort" & vbTab & "Sorted"
WScript.StdOut.WriteLine
WScript.StdOut.Write "3,2,5,4,1" & vbTab & Selection_Sort("3,2,5,4,1")
WScript.StdOut.WriteLine
WScript.StdOut.Write "c,e,b,a,d" & vbTab & Selection_Sort("c,e,b,a,d")
{{out}}
Pre-Sort Sorted
3,2,5,4,1 1,2,3,4,5
c,e,b,a,d a,b,c,d,e
XPL0
include c:\cxpl\codes; \intrinsic 'code' declarations
string 0; \use zero-terminated strings
proc SelSort(A, N); \Selection sort
char A; \address of array
int N; \number of elements in array (size)
int I, J, S, JS, T;
[for I:= 0 to N-2 do
[S:= (~0)>>1;
for J:= I to N-1 do \find smallest element
if A(J) < S then [S:= A(J); JS:= J];
T:= A(I); A(I):= A(JS); A(JS):= T;
];
];
func StrLen(Str); \Return number of characters in an ASCIIZ string
char Str;
int I;
for I:= 0 to -1>>1-1 do
if Str(I) = 0 then return I;
char Str;
[Str:= "Pack my box with five dozen liquor jugs.";
SelSort(Str, StrLen(Str));
Text(0, Str); CrLf(0);
]
{{out}}
.Pabcdeefghiiijklmnoooqrstuuvwxyz
zkl
fcn selectionSort(list){ // sort a list of ints
copy,r:=list.copy(),List();
while(copy){
min,idx:=(0).min(copy), copy.find(min);
r.append(min);
copy.del(idx);
}
r
}
selectionSort(List(28, 44, 46, 24, 19, -5, 2, 17, 11, 25, 4)).println();
{{out}}
L(-5,2,4,11,17,19,24,25,28,44,46)
{{omit from|GUISS}}